1. Statement of the Technical Field
The present invention relates to the field of geographic information systems (GIS) technology, and more particularly to a representation of an object being tracked in a three-dimensional geographic model.
2. Description of the Related Art
Computer-based object tracking systems have become available to provide object location and tracking information. For example, Automatic Vehicle Location (AVL) systems are available that utilize a Global Positioning System (GPS) to obtain data that can be used to monitor a vehicle location. The vehicle location data can be presented to a user at a monitoring station, typically via a computer interface. The user can monitor the vehicle location from the monitoring station.
In addition to a monitoring station, a typical AVL system commonly includes mobile units, a wireless communication network, and a computer system incorporating geographic information systems (GIS) technology. A mobile unit is a device that can be installed in a vehicle to enable the vehicle to be monitored and tracked, and typically includes a GPS receiver and a wireless transmitter. The mobile unit receives positioning signals from GPS satellites in the form of code sequences and converts these code sequences to pseudo range information or standard GPS code (NMEA). Pseudo ranges from a minimum of four different satellites are required in most instances for position calculation. These pseudo ranges or NMEA codes are subsequently transmitted via the wireless network to the monitoring station for position calculation.
The computer system incorporating GIS technology is usually equipped and configured to process GPS data and to monitor vehicle locations. The computer system performs filtering of the pseudo range signals or raw GPS data transmitted from the mobile units and further reduces these ranges into map coordinates for display. Current systems may also perform position corrections by using differential continuous positioning system (CPS) data obtained from a station in the vicinity of the vehicle being monitored.
Most conventional systems using GIS technology process GPS data according to two-dimensional (2D) spatial references. Still, conventional GIS technologies can be configured to process topographic data, in addition to rudimentary 2D data, usually in the form of a digital elevation model. Based upon the topographic data, isometric views and contour maps can be generated. Tracking system users, however, have recognized the limitations of a 2D modeling paradigm for modeling three-dimensional (3D) phenomena, even when combined with topographic data.
Notably, some GIS technologies can integrate scene generation systems for the 3D visualization of data, but the elevation coordinate data in these systems has been included only to xe2x80x9cdrapexe2x80x9d a two-dimensional mapping over topographic data to produce what is known as a 2.5D model. Importantly, the use of a 2.5D model ought not to be confused with 3D. The elevation information in a 2.5D model is limited to the pre-determined elevation data for a geographic surface, such a road. Accordingly, application of 2.5D models is primarily limited to monitoring motor vehicles and the like.
Notably, in a 2.5D, one elevation is typically assigned for an entire structure. Hence, floors in multilevel structures, such as high rise office buildings and apartment buildings, cannot be accurately represented in a 2.5D model. Accordingly, the current tracking technology does not provide a means for tracking personnel, for example fire fighters, as the personnel travel between floors in a multilevel structure. Further, current tracking technology cannot provide accurate 3D images from various perspectives within a scene, for example, the view of a bank from the perspective of a police officer positioned on the roof of a building located across the street from the bank.
The present invention relates to a method and a system for tracking and locating objects and representing those objects as icons within a highly accurate three-dimensional (3D) model. The present invention tracks an object, such as a person, a vehicle, or an aircraft, by generating GPS coordinates for the object and a bearing associated with a movement of the object. In particular, the GPS coordinates include a latitude, a longitude, and an altitude. Importantly, the GPS coordinates can be processed to correlate the altitude of the object with an identifier that identifies a level within a structure. An icon representing the object then can be accurately located in a first view of a three dimensional model. Further, an indicator can be associated with the icon to indicate the object""s level, a bearing of the object, and/or the object""s GPS coordinates.
The GPS coordinates of the object also can be compared with a location of a second object to generate a comparison. The comparison can be processed to determine the content of a communication that is transmitted to the object, for example a dispatch message. The communication can be transmitted wirelessly to the object and can be encrypted prior to being transmitted. The object can be a person, a vehicle, a watercraft or an aircraft. Lastly, biological statistics, mechanical statistics, fuel level, speed, velocity and other parameters of the object can be monitored.